The invention relates to a vehicle seat, particularly to a seat belt-integrated vehicle seat provided with a reclining device, the vehicle seat to which a seat belt is attached.
Conventionally, there is a known vehicle seat provided with a reclining device and a seat belt which is supported on the vehicle seat at three points and integrated with the vehicle seat. In the seat belt-integrated vehicle seat, a shoulder anchor is provided in an upper part of a side frame on the outer side of a vehicle body (that is, the vehicle door side), and a shoulder belt portion of the seat belt is attached to the upper part of the side frame on the outer side via the shoulder anchor.
In such a seat belt-integrated vehicle seat, particularly at a time of a vehicle collision, a large load from a passenger is applied onto the seat belt. Thus, a large load is imposed onto the side frame on the outer side to which the shoulder belt portion is attached. Therefore, there is a known vehicle seat in which a side frame on the outer side is formed by a support having a square closed section structure to have a higher strength than a side frame on the inner side (for example, refer to Japanese Patent Application Publication No. 2002-059770 (“the '770 Publication”)).
The vehicle seat described in the '770 Publication is provided with a reclining device in which a main side recliner of the reclining device is rotatably coupled to a lower arm and an upper arm, the lower arm is screwed and fixed only to a side plate of a main side cushion side frame by a first stepped bolt, and the upper arm is screwed and fixed only to a side plate of a main side back side frame by a second stepped bolt, so that the main side recliner is attached to the main side cushion side frame and the main side back side frame with a high precision.
However, in the vehicle seat described in the '770 Publication, a recliner arm (the upper arm) serving as a separate member is attached to the main side back side frame having a closed section structure so that this recliner arm and the reclining device are coupled to each other. Thus, there is a problem that, due to an attachment error between the members, a position precision of the reclining device and the shoulder anchor into which the shoulder belt portion is inserted may be decreased.